Container format in the context of Distinguished Encoding Rules

An audio file format is a file format for storing digital audio data on a computer system. The bit layout of the audio data (excluding metadata) is called the audio coding format and can be uncompressed, or compressed to reduce the file size, often using lossy compression. The data can be a raw bitstream in an audio coding format, but it is usually embedded in a container format or an audio data format with a defined storage layer.

Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. It was developed by Dolby, AT&T, Fraunhofer and Sony, originally as part of the MPEG-2 specification but later improved under MPEG-4. AAC was designed to be the successor of the MP3 format (MPEG-2 Audio Layer III) and generally achieves higher sound quality than MP3 at the same bit rate. AAC encoded audio files are typically packaged in an MP4 container most commonly using the filename extension .m4a.

The basic profile of AAC (both MPEG-4 and MPEG-2) is called AAC-LC (Low Complexity). It is widely supported in the industry and has been adopted as the default or standard audio format on products including Apple's iTunes Store, Nintendo's Wii, DSi and 3DS and Sony's PlayStation 3. It is also further supported on various other devices and software such as iPhone, iPod, PlayStation Portable and Vita, PlayStation 5, Android and older cell phones, digital audio players like Sony Walkman and SanDisk Clip, media players such as VLC, Winamp and Windows Media Player, various in-dash car audio systems, and is used on Spotify, Google Nest, Amazon Alexa. Apple Music, YouTube and also YouTube Music streaming services. AAC has been further extended into HE-AAC (High Efficiency, or AAC+), which improves efficiency over AAC-LC. Another variant is AAC-LD (Low Delay).

High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a proprietary video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 Part 10). The standard was published in 2013. In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality, or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD, and unlike the primarily eight-bit AVC, HEVC's higher-fidelity Main 10 profile has been incorporated into nearly all supporting hardware. The High Efficiency Image Format (HEIF) is a container format whose default codec is HEVC.

While AVC uses the integer discrete cosine transform (DCT) with 4×4 and 8×8 block sizes, HEVC uses both integer DCT and discrete sine transform (DST) with varied block sizes between 4×4 and 32×32.

The Speex project is an attempt to create a free software speech codec, unencumbered by patent restrictions. Speex is licensed under the BSD License and is used with the Xiph.org Foundation's Ogg container format.

The Speex coder uses the Ogg bitstream format, and the Speex designers see their project as complementary to the Vorbis general-purpose audio compression project.

High Efficiency Image File Format (HEIF) is a digital container format for storing individual digital images and image sequences. The standard covers multimedia files that can also include other media streams, such as timed text, audio and video.

HEIF can store images encoded with multiple coding formats, for example both SDR and HDR images. HEVC is an image and video encoding format and the default image codec used with HEIF. HEIF files containing HEVC-encoded images are also known as HEIC files and often use the .heic filename extension. Such files require less storage space than the equivalent quality JPEG.